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Programmatic access to ICTV virus taxonomy through a public ontology API.

BACKGROUND: The International Committee on Taxonomy of Viruses (ICTV) is responsible for developing and maintaining a universal virus taxonomy. As the reference framework for organising the viral world, it is essential for virology and related fields. Despite its widespread use in research and public health, programmatic access to ICTV taxonomy has remained limited, posing challenges for integration, versioning, and interoperability across databases and bioinformatics resources requiring up-to-date virus taxonomy. FINDINGS: To address this, we developed a public and sustainable solution leveraging ontology-based APIs. All available ICTV Master Species List (MSL) releases, from MSL1 to MSL41, were transformed into a unified, semantically structured ontology comprising more than 195,000 current and historical entities and deployed through the Ontology Lookup Service (OLS). The ontology is automatically rebuilt and republished whenever a new MSL release becomes available. Complementary ICTV-NCBI mappings and helper libraries support integration into downstream systems. CONCLUSIONS: Together, these resources enable, for the first time, public programmatic retrieval of current and historical ICTV taxon names, taxonomic relationships, metadata, and persistent identifiers through stable endpoints, including resolution of former taxonomic terms to their current accepted taxon or taxa and retrieval of taxon histories across releases. More broadly, this work illustrates a general strategy for transforming structured biological datasets into semantically enriched graph resources exposed through scalable public APIs. These developments enhance interoperability, reduce manual curation, and support FAIR-aligned taxonomic data management in virology and pandemic preparedness.

API

Programmatic access to ICTV virus taxonomy through a public ontology API.

The International Committee on Taxonomy of Viruses (ICTV) is responsible for developing and maintaining a universal virus taxonomy. As the reference framework for organising the viral world, it is essential for virology and related fields. Despite its widespread use in research and public health, programmatic access to ICTV taxonomy has remained limited, posing challenges for integration, versioning, and interoperability across databases and bioinformatics resources requiring up-to-date virus taxonomy. To address this, we developed a public and sustainable solution leveraging ontology-based APIs. Successive ICTV Master Species List (MSL) releases were transformed into a structured ontology and deployed as a unified representation through the Ontology Lookup Service (OLS). The framework also provides ICTV-NCBI mappings and helper libraries for integration into downstream systems. This enables, for the first time, public programmatic retrieval of current and historical virological taxon names, taxonomic relationships, metadata, and persistent identifiers through stable endpoints. More broadly, this work illustrates a general strategy for transforming structured biological datasets into semantically enriched graph resources exposed through scalable public APIs. These developments enhance interoperability, reduce manual curation, and support FAIR-aligned taxonomic data management in virology and pandemic preparedness.

API

The complete genomic sequence of a novel member of the genus Caulimovirus isolated from Dregea volubilis.

A novel caulimovirus was identified from diseased leaves of Dregea volubilis exhibiting yellowing and vein-associated chlorosis in Yuanjiang County, Yunnan Province, China. The virus was tentatively named Dregea volubilis caulimovirus 1 (DVCaV1). The complete genome sequence of DVCaV1, determined by de novo assembly of high-throughput sequencing data, comprises 8,160 bp of circular double-stranded DNA containing two intergenic regions and seven open reading frames (ORFs). These ORFs encode (in order) a movement protein (MP), an aphid transmission factor (ATF), a virion-associated protein (VAP), a coat protein (CP), a polymerase polyprotein (Pol, containing protease, reverse transcriptase, and RNase H domains), a transactivator/viroplasmin (TAV) protein, and a hypothetical protein of unknown function. Sequence comparisons revealed the highest nucleotide similarity with strawberry vein banding virus (SVBV; NC_001725). Phylogenetic analysis confirmed DVCaV1 as a member of the genus Caulimovirus, with SVBV as its closest known relative. According to current ICTV species demarcation criteria for the genus Caulimovirus (host range and > 20% nucleotide sequence divergence in the polymerase region), DVCaV1 represents a novel species. This is, to our knowledge, the first report of a caulimovirus detected in naturally symptomatic Dregea volubilis.

Genome, Viral

Molecular characterization and genome sequence analysis of Dichroa emaravirus, a putative novel member of the genus Emaravirus.

Hydrangea febrifuga (syn. Dichroa febrifuga) is a traditional medicinal plant distributed in China and Southeast Asia, and febrifugine, one of its principal bioactive constituents, has served as an important lead compound for antimalarial drug development. Viral infections may adversely affect the quality of medicinal plants; however, no emaravirus has previously been reported from H. febrifuga. Here, high-throughput sequencing was performed on H. febrifuga leaves exhibiting mosaic symptoms collected in Yunnan Province, China. Combined with RT-PCR, Sanger sequencing, and 5'/3' rapid amplification of cDNA ends (RACE), five full-length genomic RNA segments of a putative novel emaravirus, tentatively designated Dichroa emaravirus (DEV), were identified and characterized. The five negative-sense single-stranded RNA (-ssRNA) segments have a combined length of 12,971 nt and encode an RNA-dependent RNA polymerase (RdRp), glycoprotein precursor (GP), nucleocapsid protein (NP), movement protein (MP), and an uncharacterized accessory protein, P5. The maximum amino acid sequence identities of DEV P1-P4 with recognized emaraviruses were 73.90%, 51.82%, 65.60%, and 81.30%, respectively, whereas P5 showed a maximum identity of 49.16% with its closest homolog. Thus, three of the four core proteins had maximum identities below 80%, consistent with the current ICTV species demarcation criterion for the genus Emaravirus. Maximum-likelihood phylogenetic analyses based on the four core proteins further supported the placement of DEV within the genus Emaravirus (family Fimoviridae). These results support DEV as a putative novel emaravirus and represent the first report of an emaravirus associated with H. febrifuga.

Genome, Viral

A novel transformer model of protein domains for viral taxonomy classification.

MOTIVATION: Viruses with carefully curated taxonomic assignments (such as those in the ICTV taxonomy) still represent only a small fraction of viruses identified through sequencing data from virome or microbiome projects. It is therefore critical to develop methods that can assign viruses at multiple taxonomic ranks, so that a virus deemed novel at a given rank may still be placed into a higher-level taxon. Sequence-similarity-based approaches can classify viruses that share substantial genomic similarity with known viruses (e.g. those belonging to the same species or genus); however, their performance drops significantly when applied to more divergent viruses. Recent deep learning models, such as ViTax, which utilize DNA language models, aim to address these limitations, but their performance also degrades when applied to novel viruses lacking genus-level similarity to known references. Proteins are more conserved than genomic sequences, and the multiple proteins encoded by a virus can be leveraged to reveal evolutionary relationships among viruses. RESULTS: We propose a new tool, D2T (Domain-to-Taxonomy), that leverages recent advances in protein language models to improve viral taxonomic assignment. D2T represents a virus as a sequence of protein domain tokens and learns a transformer-based model for taxonomic classification. Experiments on multiple closed-set and open-set datasets show that D2T excels at assigning higher-level taxonomic labels (family and above). Furthermore, by combining D2T with Kraken2, which performs well at the genus level, the hybrid method (K+D2T) achieves accurate viral taxonomic classification across multiple taxonomic ranks. AVAILABILITY AND IMPLEMENTATION: D2T is available as a GitHub repository at https://github.com/mgtools/D2T.

Viruses

Metagenomics reveals cryptic circulation of zoonotic viruses in Nigeria.

Zoonotic spillover events pose an ongoing threat to global health, with historic and recent viral diseases of international concern emerging from animal reservoirs 1-6. In Nigeria, limited surveillance of animal hosts at the human and animal interface continues to hinder our understanding of viruses that are cryptically circulating in animals near human dwellings with potential for consequential spillover events. We performed unbiased metagenomic next-generation sequencing (mNGS) on tissue and swab samples collected from 240 individual animals across 11 taxa (rodents, shrews, bats, goats, sheep, pigs, dogs, cats, chickens, cattle egrets, and lizards) in two Lassa-affected Nigerian states (Ondo and Ebonyi). Host-depleted sequencing reads were assembled into contigs, taxonomically classified, and subjected to phylogenetic analyses to characterize viral diversity, host associations, and evidence of cross-species transmission. Across all samples, we identified 214 distinct viral taxa spanning 33 families, of which 41% (n = 83) represent novel species by ICTV criteria. Positive-sense RNA viruses dominated (Coronaviridae, Picornaviridae, Astroviridae), followed by negative-sense RNA, single- and double-stranded DNA, and double-stranded RNA viruses. Notably, human-associated enteroviruses-including Hepatitis A virus (genotype 1b), echoviruses, coxsackieviruses, and noroviruses-were detected in goats, pigs, dogs, and chickens, indicating cryptic circulation of human pathogens in peridomestic and domesticated animals. Phylogenetic reconstructions revealed multiple cross-species viral sharing events, particularly among rodents, goats, sheep, and pigs, and extensive recombination within Nigerian Betacoronavirus 1 lineages. Interestingly we found a putative novel avian like coronavirus in rodents, goats and sheep. Ecological modelling demonstrated that host species identity, sample type, and sampling effort were primary drivers of viral richness and abundance, and that higher overall viral diversity strongly predicted cross-species transmission potential. Our integrated mNGS approach uncovered a rich and dynamic virome within animals inhabiting human-dominated environments in Nigeria, including undetected circulation of human enteric viruses. These findings underscore the importance of broad-taxonomic, real-time surveillance at human-animal interfaces to inform early-warning systems and pandemic preparedness, particularly in low-resource settings.

Journal Article

Genomic and functional characterization of novel therapeutic lytic bacteriophages targeting multidrug-resistant Enterobacter cloacae.

The alarming rates at which extensively drug-resistant (XDR) and pandrug-resistant (PDR) Enterobacter cloacae in hospitals are increasing has begun to severely limit treatment options, and thus the urgency for alternative interventions, including bacteriophage therapy. The purpose of the study was to isolate and molecularly characterize phages that can infect E. cloacae, and, furthermore, to assess the antimicrobial efficacy of the four novel lytic bacteriophages (MMRP1, MMRP2, MMRP3, and MMRP4) against antimicrobial-resistant E. cloacae isolates and to evaluate their potential as alternative therapeutic strategies. These novel phages were characterized by plaque morphology, transmission electron microscopy (TEM), host range testing, thermal and chloroform stability assays, bacterial reduction assays, and whole-genome sequencing (WGS). Among 27 clinical isolates, MDR, XDR, and PDR phenotypes were observed in 20 (74.1%), six (22.2%), and one (3.7%) isolates, respectively. All four phages produced clear lytic plaques (0.5-3.0 mm) with titers reaching up to 6 × 1010 PFU/mL, and the phage cocktail lysed 81.4% (22 of 27 isolates) of clinical isolates with high host specificity. TEM revealed that all four E. cloacae-infecting phages (MMRP1, MMRP2, MMRP3, and MMRP4) belong to the class Caudoviricetes, exhibiting icosahedral capsids, tailed morphology, and double-stranded DNA genomes, consistent with current ICTV classification criteria. Whole genome sequencing and comparative phylogenetic analysis further resolved the taxonomic placement of these phages at the family level, positioning MMRP1 within the family Demerecviridae and MMRP4 within the family Straboviridae. All phages were stable from -20 to 40 °C and were unaffected by exposure to chloroform. Phage cocktail reduced bacterial OD₆₀₀ to ≤ 0.3 within 4 h in the bacterial reduction test. WGS revealed large circular dsDNA genomes of ~132 kbp (MMRP1) and ~149 kbp (MMRP4), GC content of 38%, and modular architectures encoding structural, lytic, and replication gene modules. The most striking and highlighted suggestion that in vitro evaluation of MMRP1 and MMRP4 are highly recommended to more deeper future experimental studies to combat MDR E. cloacae nosocomial infections supported by genomic foundation and eventually, the possibility to be suitable for phage-engineering applications in clinical settings.

Enterobacter cloacae